Study of plasma termination using high-<i>Z</i>noble gas puffing in the JT-60U tokamak

Bakhtiari, M.; Tamai, Hiroshi; Kawano, Y.; Kramer, G. J.; Isayama, A.; Nakano, T.; Kamiya, Yukihide; Yoshino, R.; Miura, Y.; Kusama, Y.; Nishida, Yasushi

doi:10.1088/0029-5515/45/5/002

Cited by 50 publications

(45 citation statements)

References 20 publications

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“…Thus, a mitigation technique has to provide a reliable suppression of this avalanche mechanism. Presently, massive gas injection is discussed as a technique to mitigate forces and heat loads and also to suppress runaway generation [20][21][22][23][24][25][26]15]. However, the latter aim might have severe implications which are not easily overcome.…”

Section: Runaway Dynamics and Wall Interactionmentioning

confidence: 99%

Runaway generation during disruptions in JET and TEXTOR

Lehnen¹,

Abdullaev²,

Arnoux

et al. 2009

Journal of Nuclear Materials

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Runaway electrons generated during ITER disruptions are of concern for the integrity of the plasma facing components. It is expected that a power of up to 8 GW is exposed to ITER PFCs. We present in this article observations from JET and TEXTOR on the generation of runaways and the heat load deposition. Suppression techniques like massive gas injection and resonant magnetic perturbations are discussed.

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Section: Runaway Dynamics and Wall Interactionmentioning

confidence: 99%

Runaway generation during disruptions in JET and TEXTOR

Lehnen¹,

Abdullaev²,

Arnoux

et al. 2009

Journal of Nuclear Materials

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“…For the densities reached in TEXTOR (n e ≤ 2 · 10 14 cm −3 ) the coronal limit is still sufficient [31,32]. Previously a systematic study of REs after gas injection was performed in JT-60U [34,35] by using fueling valves (injection time ∼ 100 ms, flow rates ∼ 5 · 10 21 atoms/s). Injections of argon, krypton or xenon were found to provoke RE generation, while by simultaneous injection of one of these gases with deuterium through two separate valves it was possible to avoid runaways.…”

Section: Electrons (Equation 2)mentioning

confidence: 99%

Generation and suppression of runaway electrons in disruption mitigation experiments in TEXTOR

Bozhenkov¹,

Lehnen²,

Finken³

et al. 2008

Plasma Phys. Control. Fusion

122

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Abstract. Runaway electrons represent a serious problem for the reliable operation of the future experimental tokamak ITER. Due to the multiplication factor of exp(50) in the avalanche even a few seed runaway electrons will result in a beam of high energetic electrons that is able to damage the machine. Thus suppression of runaway electrons is a task of high importance, for which reason we present here a systematic study of runaway electrons following massive gas injection in TEXTOR. Argon injection can cause generation of runaways carrying up to 30% of the initial plasma current, while disruptions triggered by injection of helium or of mixtures of argon (5, 10, 20%) with deuterium are runaway free. Disruptions caused by argon injection finally become runaway free for very large amounts of injected atoms. The appearance/absence of runaway electrons is related to the fraction of atoms delivered to the plasma center. This so called mixing efficiency is deduced from a 0D model of the current quench. The estimated mixing efficiency is: 3% for argon, 15% for an argon/deuterium mixture and about 40% for helium. A low mixing efficiency of high-Z impurities can have a strong implication for the design of the disruption mitigation system for ITER. However, a quantitative prediction requires a better understanding of the mixing mechanism.

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“…The photoionization of krypton ions is of particular interest in the determination of elemental abundances in stars and planetary nebulae [3], as well as in inertial-confinement fusion experiments [4]. Injection of Kr gas has been demonstrated to mitigate disruption in magnetically confined Tokamak fusion plasmas [5].…”

Section: Introductionmentioning

confidence: 99%

Valence-shell single photoionization of Kr+ions: Experiment and theory

et al. 2012

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Photoionization of Kr+ ions was studied in the energy range from 23.3 eV to 39.0 eV at a photon energy resolution of 7.5 meV. Absolute measurements were performed by merging beams of Kr + ions and of monochromatized synchrotron undulator radiation. Photoionization (PI) of this Br-like ion is characterized by multiple Rydberg series of autoionizing resonances superimposed on a direct photoionization continuum. Resonance features observed in the experimental spectra are spectroscopically assigned and their energies and quantum defects tabulated. The high-resolution cross-section measurements are benchmarked against state-of-the-art theoretical cross-section calculations from the Dirac-Coulomb R-matrix method [1].

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Study of plasma termination using high-Znoble gas puffing in the JT-60U tokamak

Cited by 50 publications

References 20 publications

Runaway generation during disruptions in JET and TEXTOR

Runaway generation during disruptions in JET and TEXTOR

Generation and suppression of runaway electrons in disruption mitigation experiments in TEXTOR

Valence-shell single photoionization of Kr+ions: Experiment and theory

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